4.3 Lab Flashcards
Cyanobacterial alkaloid neurotoxins - example and effects
Common source : Anabaena , Oscillatoria sp. Neurotoxin : Anatoxin-a
aka Very Fast Death Factor, a neurotoxin
Animals affected: sheep, cattle, dogs, pigs & birds
Poisoning circumstances: Many blooms non-toxic, but all should be considered potentially toxic
Main effect: Sudden death (respiratory paralysis)
mechanism of action of anatoxin-a
Anatoxin-a is a potent irreversible agonist of acetylcholine receptors present in the CNS and at the neuromuscular junction
>muscle unable to contract
what are two cyanobacterial toxins that affect the liver?
microcystins, nodularin
what are two cyanobacterial neurotoxins?
saxitoxins: nerve axons
anatoxin-a: nerve synapse
what do we think of when we see: Slight dark brown discoloration of ocular mucous membranes, heart blood, muscle and mammary gland
methemoglobinemia
**mechanism of nitrate toxicity in ruminant, and result
Nitrates (water contamination, young green feed, etc)
>Convert to even more toxic nitrite (by rumen flora)
>Nitrite binds to Fe3+ in heme Oxidation to methemoglobin
>Hypoxia and vasodilation (nitric oxide/NO)
=>Methemoglobinemia
ante mortem signs of nitrate toxocity
Muddy colour mucous membranes
Measure NO3 (serum, urine) >30 ppm
Test suspect forages & water
post mortem signs of nitrate toxicity
Muddy colour mucous membranes and tissues
Ocular fluid NO3 (>20 ppm) (also other fluids)
Test suspect forages
Rumen content not useful - unstable
Etiology of nitrate/nitrite intoxication
Toxicosis most commonly from ingestion of plants (ie. hungry ruminants)
Can also result from accidental ingestion of fertilizers
Crops that concentrate NO3: oats, millet, rye, sunflower, corn and sorghums
Also many weeds: pigweed, jimson weed
clinical findings associated with nitrate toxicity
Signs of NO3 poisoning rapid due to hypoxia and low blood pressure (vasodilation)
Weak heartbeat, tremors and ataxia
Brown, cyanotic mucous membranes with >50% metHb
Sudden death may be within 1 hr
pathology: non-specific - congestion of major organs, signs of terminal struggle or seizure
product added to animal feed to artificially inflate the ‘protein’ level (nonprotein nitrogen) of the feed (bad news)
melamine
what are sources of melamine?
Melamine found in wheat gluten, rice protein concentrate, and corn gluten exported from China
effects of melamine consumption - what body systems does it effect?
urinary system, eg. kidney stones
when should emesis not be induced?
if the animal:
-has already vomited
-is very drowsy or unconscious
-is exhibiting seizure activity
-has reduced cough reflex
-has an underlying condition which predisposed them to aspiration
if the substance ingested:
-is likely to cause rapid onset of drowsiness or seizures
-contains paraffin, petroleum products, or other oily or volatile organic products which could be aspirated into the lungs
-contains detergent compounds, which could be aspirated into the lungs
-is a strong acid or alkali, which could cause further damage to the esophagus if regurgitated
common way for dogs to get access to tremorgens?
-access to garbage and compost with mouldy food
-eg. roquefortine from penicillium roqueforti, penitrem a by penicillium crustosum